Fillets vs. Cleats

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OneWayTraffic
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Re: Fillets vs. Cleats

Post by OneWayTraffic »

What's the cause of the flaking? Aside from that I don't see the cleats or the fillet giving way.

jonnymac
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Re: Fillets vs. Cleats

Post by jonnymac »

OneWayTraffic wrote: Sat Dec 04, 2021 12:27 am What's the cause of the flaking? Aside from that I don't see the cleats or the fillet giving way.
he hit a submerged object and the tape pulled off the transom.

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OrangeQuest
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Re: Fillets vs. Cleats

Post by OrangeQuest »

jonnymac wrote: Sat Dec 04, 2021 6:03 am
OneWayTraffic wrote: Sat Dec 04, 2021 12:27 am What's the cause of the flaking? Aside from that I don't see the cleats or the fillet giving way.
he hit a submerged object and the tape pulled off the transom.
Yes, the tape pulled away, but the transom looks like the epoxy is still stuck to the wood of the transom where it is coated, then glassed the transom and after a few days, weeks, added the cheats, deck and tape? Was the area where it is glued the cheat to, roughed up and sanded before adding the cleat, deck, and tape?
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
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jonnymac
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Re: Fillets vs. Cleats

Post by jonnymac »

Yes that’s very interesting point. I hope maybe in the interest of helping people out he will post more close up pictures.

If the tape couldn’t take the force it would have ripped vs coming off in one piece. so does seem to indicate it was secondary bond failure. And that is relevant to this discussion about cleats vs fillets, that if you don’t get good bonding it doesn’t matter which method you chose. So choose the method that you personally can best achieve good bonding with.
OrangeQuest wrote: Sat Dec 04, 2021 7:44 am
jonnymac wrote: Sat Dec 04, 2021 6:03 am
OneWayTraffic wrote: Sat Dec 04, 2021 12:27 am What's the cause of the flaking? Aside from that I don't see the cleats or the fillet giving way.
he hit a submerged object and the tape pulled off the transom.
Yes, the tape pulled away, but the transom looks like the epoxy is still stuck to the wood of the transom where it is coated, then glassed the transom and after a few days, weeks, added the cheats, deck and tape? Was the area where it is glued the cheat to, roughed up and sanded before adding the cleat, deck, and tape?

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OrangeQuest
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Re: Fillets vs. Cleats

Post by OrangeQuest »

Yes JonnyMac, I thought it was crazy that the boat builders got hung up/focused on the height of the transom rather than looking at what was going on with the bond. I am not saying it was a bad bond, not the best it could have been, but that needs to be addressed when making the repairs.

Fallguy goes over the secondary bond over and over and how to have/get the absolute best results and why it is so important. His lectures on it has me double checking my methods. He should write a bible on fiber glassing when he is done with his boat.

Hard to tell in the pictures but looks like behind where it pulled loose is a little shiney.
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
A. A. Milne

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Re: Fillets vs. Cleats

Post by Fuzz »

The bonding issue is why I have always wondered about the best way of doing things. When building it is nice to coat the wood to seal it and to keep it dry. But if you do that then you have the secondary bond issue to deal with. Clearly the best way is to do all glassing within the primary bond window but you either need a full crew or be superman.

TomW1
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Re: Fillets vs. Cleats

Post by TomW1 »

You don't have to do wet on wet. Epoxy will still give you a chemical bond up to 36 to 48 hours depending on the temperature and dependeing if you are using slow or fast speed hardener. The epoxy is still green and the new applied epoxy will wake it up to form a chemical bond.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Re: Fillets vs. Cleats

Post by BarraMan »

I'm not going to argue the difference between primary and secondary bonds - the chemistry is quite clear, but ............ here is my perspective! 8O

I built 90% of my boat solo! My wife helped with large glassing runs, ie I wet out the glass cloth and she chased air bubbles. Air bubbles came to fear her as she was relentless! :lol: She also helped with painting - I rolled and she tipped!

Its a BIG boat at 22' and I just don't think you can expect to get primary bonds all the time - so I accepted mostly secondary bonding. That said, there was probably no more that 24 hrs between glass layers so there may have still been some primary bonding in play. I roughed up the previous layer of epoxy with 80 grit using various sanders or manually for difficult to get at places. I was pretty meticulous with my glassing and was very happy with my work, at the end of the day.

After 400 hours over 5 years in service, almost to the day, the boat remains solid as a rock! I inspect it regularly and run a small hammer over it as part of my preparation for one of my fishing pilgrimages.

So I think that primary bonds are OK where you can get them, but secondary bonds are just fine, providing you do the appropriate preparation.

Just my 2 cents worth! :D

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Re: Fillets vs. Cleats

Post by OneWayTraffic »

The strength is engineered in. The actual strength of the bond is not the issue. The reliability is. Let's say that a secondary bond is half the strength of a primary. No worries, just use bigger overlaps on the glass. Problems arise when there is variability of strength. Then it's hard to know how much is enough. Designers put in large safety margins for this.

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Re: Fillets vs. Cleats

Post by OneWayTraffic »

If anyone is interested in how the professionals deal with primary vs secondary, this is interesting reading. Powerpoint type presentation.

https://www.aerodefevent.com/wp-content ... rials.pdf

I learned something by reading it: Especially this.
• The region around the interface that determines bond performance is only ~6 molecules thick
• A fingerprint is ~1000 molecules thick
• Residue from a human breath can be ~40-100 molecules thick
• A properly prepared surface is chemically reactive and very delicate
• Properties change very quickly with (seemingly) small changes in environment, handling, out time

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